Text from page-3

Experiment No:
THERMOCOUPLE
AIM OF EXPERIMENT: To determine the temperature traducers thermocouple,
thermister and Bimetallic by using digital temperature indicator.
APPARATUS REQUIRED:
Temperature transducers, digital Temperature indicator, Thermometer, Electric Sterilizer,
Bimetallic temperature indicator.
Type of sensor: “J” type, “K” type and “T” type
Material Used: J – Chromium Alumel
K – Tungsten steel
T – Manganes, Nickel, Copper, Iron and Uranium
THEORY: The Thermocouple is one of the simplest and most commonly used
methods of measuring process temperature. The operation of thermocouple is based upon
see back effect. See back discovered that when is applied to junction (hot junction) of two
dissimilar metals, an emf is generated which can be measured at the other junction (cold
junction). The two dissimilar metals from an electric circuit and a current flows as a
result of the generated emf.
A pair of two dissimilar metals that are in physical contact with each other from a
thermocouple. These metals welded together. Thermocouples do not use bare conductors
except in applications where atmospheric condition permit their use. These condition
obtained when temp. to be measured are low and the atmosphere is non-corrosive.
Industrial thermocouples employ protective sheathing surrounding the junction and a
portion of the extension leads The leads and the junction are internally insulated from the
sheath, using various potting compounds, ceramic beads or orides. The type of insulation
used depends upon the process being monitored.
OPERATION:1. Select the thermocouple by selector switch.
2. Connect the thermocouple, Thermister and Bimetallic to the sensor socket
provided at the front panel.
3. Set the min pot to read the ambient temp. in display.
4. Insert the thermocouple, Thermister and Bimetallic in the HOT bath.
PREPARED BY ER. MANOJ KUMAR ROUT
Page 3